Fluid type attrition mill and separator



Sept. 1950 H. L CROWLEY :rm. 2,521,000

FLUID TYPE A'ITRITION MILL AND SEPARATOR Filed Jan. 5, 1945 INVENTOR. Henry L Crow/e3 By 0w/n F NOSf/mf A45 hland 6. Henderson %CUJ -T Patented Sept. 5, 1950 FLUID TYPE ATTRI'IION MILL AND SEPARATOR Henry L. Crowley, South Orange, Edwin F. Mosthai', Orange, and Ashland S. Henderson, Caldwell, N. J said Mostha! and said Henderson assignors to said Crowley Application January 5, 1945, Serial No. 571,466

6 Claims. 241-39) This invention relates specifically to a gas attrition type mill in which particle movement is accomplished by the use of fans.

A primary object of this invention is to perform particle attrition without the use of a separate compressed air source.

Another object is to provide continuous particle attrition with a mill which can be inserted into a classifying system. v

A further object of this invention is to provide a particle attrition mill which is capable of variation, depending upon the particle size desired and the material being handled in the circuit.

Still a further object is to perform the attrition in a mill which can be economically operated with an inert atmosphere under pressure.

Other and further objects will be apparent from the following disclosure and appended claims.

In the accompanying drawing, the single figure diagrammatically illustrates the complete mil] with some parts in cross-section and others in elevation.

It is general practice in air attrition mills, such as disclosed in Patent No. 2,191,095, to Albert C. Hobbie, to obtain particle velocit and turbulence within the unit by the use of a number of tangential ai streams moving at high velocity. As is readily apparent to one skilled in the art, the amount of energy required to compress the air or gas is quite large in this type of unit; and because of the oxidizing nature of air when used as the carrying medium, it has been difficult to use this type of mechanism in grinding materials which are oxidizable. Furthermore, many dust explosions have been started in machines of this type. Because of the large amounts of gas used in an apparatus of this type, it has heretofore been impracticable to use an inert gas as the carrying medium except in very exceptional installations.

In an attrition mill of th type disclosed in said patent, the particles are attrited one b another. That is, the grinding is accomplished by the particles bombarding each other. Such a condition is, of course, of considerable importance where work-hardening of the particles is to be avoided. There is another well-known means of obtaining these results; namely, the Eddy mill, in which the particles are thrown against one another by fans. However, the Eddy mill is objectionable because of difficulties which arise when using the mill in a closed circuit grinding system, and it has, consequently, found little industrial use.

The advantages of attrition mills of the type disclosed herein are readily apparent from the accompanylng drawing and consist essentially ofa pair of adjustable fans relativel positioned to blow gas at right angles to one another, producing turbulence in a closed space in which the fans operate. This turbulence extends throughout a return bend or loop section, where the particles are bombarded against each other and ground by attrition.

One practical physical form of the apparatus in accordance with this invention is illustrated in detail in the accompanying drawings. As shown, it includes a housing comprising a portion ll preferably of cylindrical cross-section, and a lateral tubular extension ll likewise preferably of circular cross-section. The lower end of the portion I0 is flanged and is closed by means of suitable closure and gasket members l2 attached to the flange in any suitable manner. Slidably mounted in the closure member 12 is a bearing l3 in which is journalled a shaft l4 having a fan It on the inner end thereof positioned to rotate on the axis of the portion H). An adjusted position of the fan I5 and its bearing I3 is illustrated in dotted lines. Similarly, the flanged end of the lateral extension II is closed by a gasket closure member l6 secured in any suitable manner, not shown, and supporting a bearing member I1 in which is rotatably mounted a shaft I 8 having a fan I9 on its inner end. Similarly the fan II and its bearing H are shown in an adjusted position in dotted lines.

The tubular extension II in turn has a lateral circular extension 20, shown as terminating in the plane of the upper end of the portion l0. The ends of the portion l0 and extension 20 are united by a flanged return bend 2| secured to the flanged ends thereof in any suitable manner to form a closed circulatory loop with the housing portions l0 and H. The portion [0, the extensions II and 20 and the return bend 2| thus define a closed circulatory path for the material being worked upon during the attrition or comminution thereof and for the gaseous medium in which this material is suspended. The bend 2| is provided with a discharge connection 22. The lateral extension II is also provided with a material and gas inlet connection 23 having a material inlet branch 24. The portion of the extension II to the right of the fan l9 defines a receiving chamber to which the material to be comminuted and a necessary make-up amount of the gaseous medium are supplied. It will be noted that the fans l5 and I! are mounted for rotation in planes at right angles to each other. The fans and their material flowing through the circuit.

operating shafts are longitudinally adjustable within the respective housing portions, as indicated by the double headed arrows. This adjustment can be accomplished either by lon itudinally positioning the shafts I4 and iii in their respective bearing members I3 and H or, more preferably, by longitudinally positioning the bearing members I3 and H which can be locked in various longitudinal positions within the associated closure members in any suitable manner,

not shown.

that the particles will be drawn to and through the fan l9 and driven to the left into section l and upwardly through the return bend 2i and back into extension i I. The particles flow at high velocity in a turbulent condition in this circuit impinging upon each other or bombarding each other so that the desired attrition of the particles is accomplished. The amount of attrition and particularly the rate of attrition can be varied by varying the longitudinal position of the fans l5 and I9. The finished product is withdrawn through the connection 22 and preferably at a predetermined rate, as, for example, at the rate of per unit of time of the amount of Under these conditions, the fresh incoming material through the connection 24 can be proportioned in quantity to make up for the quantity of the finished product being withdrawn through the connection 22.

As a further specific example of the operation of this apparatus the following actual operation was eilected. Fan i9 was 16" in diameter and was positioned directly below opening of the adjacent end of the return bend 2| and operated at 3,400 revolutions per minute. Fan l5 was 8" in diameter and was set about 1" above the level of the side extension II and operated likewise at 3,400 revolutions per minute. A powdered iron aggregate, such as obtained by the process in the Williams and Henderson application Serial No. 507,668, filed October 26, 1943, now Patent No. 2,418,148, issued July 3, 1946, was broken to approximately 80 mesh size in a hammer mill.

. This material was fed through the inlet 24 at a continuous rate. The finished product was withdrawn continuously at a rate of about 10% of the total through the connection 22. This re- Q covered dust-like product was continuously classifled into a material -325 mesh and all the heavier material was returned to the mill.

able variation, and we do not, therefore, desire to be strictly limited to the single illustrative embodiment herein shown but rather by the claims granted us.

What is claimed is:

1. An attrition mill, comprising means forming a closed circulatory path for a gaseous medium and a solid material which is to be comminuted in said mill and which is in suspension in said gaseous medium, said path forming means including a portion providing a substantially vertical leg of said path which is of large cross-sectional area, a substantially horizontal leg of said path provided by a lateral extension of said portion intersecting said vertical leg, and a return portion connecting the upper end of said vertical leg with said horizontal leg at a point spaced from said vertical leg; passage means connected with said path remote from said vertical leg pro-' viding for the introduction of gaseous medium and solid material to be comminuted into the circulation in said closed path, passage means connected to said path at a point remote from said vertical leg and between said vertical leg and the connection of the first named passage means with said path for the removal of gaseous material and comminuted solid material from said closed path; a fan located adjacent to the first named point and effective to move said gaseous medium and the solid material suspended therein in said closed path in a direction from said horizontal leg toward said vertical leg, and a propeller type axial fiow fan disposed for rotation about a substantially vertical axis centrally of said vertical leg, said propeller type fan being located adjacent to the lower end of said vertical leg and arranged to cause upward movement of the circulating medium and suspended materials in said vertical leg, whereby to create a zone of turbulence in said vertical leg at and adjacent to the intersection thereof with said horizontal leg providing a desired comminuting action on said suspended solid material.

2. An attrition mill, comprising means forming a closed circulatory path for a. gaseous medium and a solid material which is to be comminuted in said mill and which is'in suspension in said gaseous medium, said path forming means including a portion providing a substantially vertical leg of said path which is of large cross-sectional area, a substantially horizontal leg of said path provided by a lateral extension of said portion intersecting said vertical leg, and a return portion connecting the upper end of said vertical leg with said horizontal leg at a. point spaced from said vertical leg and from the end-of said horizontal leg remote from said vertical leg; a propeller type axial flow fan disposed for rotation about a substantially horizontal axis extending centrally along said horizontal leg, said fan being located adjacent to said first named point and effective to move said gaseous medium and the solid material suspended therein along said horizontal axis and through said horizontal leg to ward said vertical leg; the portion of said horizontal leg extending between said fan and the remote end thereof providing a receiving chamber for material to be comminuted and gaseous medium, passage means connected with said receiving chamber for the introduction of gaseous medium and solid material to becomminuted, passage means connected to said returnv portion of said circulatory path for the removal of gaseous medium and comminuted solid material from said path, and a second propeller type axial flow fan disposed for rotation about a substantially vertical axis centrally of said vertical leg, said second fan being located adjacent to the lower end of said vertical leg and arranged to cause movement of the circulating medium and suspended material in said vertical leg, whereby to create a zone of turbulence in said vertical leg at and adjacent to the intersection thereof with said horizontal leg providing a desired comminuting action of said suspended solid material.

3. An attrition mill, comprising means forming a closed circulatory path for a gaseous medium and a solid material which is to be comminuted in said mill and which is in suspension in said gaseous medium, said path forming means including a portion providing a substantially vertical leg of said path which is of large cross sec tional area, a substantially horizontal leg of said path provided by a lateral extension of said portion intersecting said vertical leg adjacent to the lower end thereof, and a return portion connecting the upper end of said vertical leg with said horizontal leg at a point spaced from said vertical leg; passage means connected with said path remote from said vertical leg providing for the introduction of gaseous medium and solid material to be comminuted into the circulation in said closed path, passage means connected to said path at a point remote from said vertical leg and between said vertical leg and the connection of the first named passage means with said path for the removal of gaseous medium and comminuted solid material from said closed path; a fan located adjacent to the first named point and effective to move said gaseous medium and the solid material suspended therein in said closed path in a I direction from said horizontal leg toward said movement of the circulating medium and suspended materials in said vertical leg, and bearing desired comminutin action on said suspended solid material.

4. An attrition mill, comprising means forming a closed circulatory path for a gaseous medium and a solid material which is to be comminuted in said mill and which is in suspension in said gaseous medium, said path forming means including a portion providing a substantially vertical leg of said path which is of a large cross sectional area, a substantially horizontal leg of said path provided by a lateral extension of said portion intersecting said vertical leg, a second vertical leg intersecting said horizontal leg at a zone spaced from the first named vertical leg. and a return portion connecting the upper ends of said vertical legs; passage means connected with said path remote from said first named vertical leg providing for the introduction of gaseous medium and solid material to be comminuted into the circulation in said closed path, passage means connected to said path at a point remote from said first named vertical leg and between said first named vertical leg and the connection of the said first named passage means with said path for the removal of gaseous medium and comminuted solid material from said closed path; a propeller type axial flow fan disposed for rotation about a substantially horizontal axis extending centrally along said horizontal leg, said fan being located adjacent to said zone and efi'ective to move said gaseous medium and said solid material suspended therein along said horizontal axis and through said horizontal leg toward said first vertical leg, bearing means for supporting said fan in different, axially adjusted positions within and adjacent to said zone, so as to control the degree of turbulence particularly in said horizontal leg of said path, and a secondpropeller type axial flow fan disposed for rotation about a substantially vertical axis centrally of said first named vertical leg, said second fan being located adjacent to the lower end of said first named vertical leg and arranged to cause upward movement of the circulating medium and suspended materials in said first named vertical leg, whereby to create a zone of turbulence in said first named vertical leg at and adjacent to the intersection thereof with said horizontal leg providing a desired comminuting action on said suspended solid material.

5. An attrition mill, comprising means forming a closed circulatory path for a gaseous medium and a solid material which is to be comminuted in said mill and which is in suspension in said gaseous medium, said path forming means including a, portion providing a substantially vertical leg of said path which is of a large cross sectional area, a, substantially horizontal leg of said path provided by a lateral extension of said portion intersecting said vertical leg adjacent to the lower end thereof, a second vertical leg intersecting said horizontal leg at a zone spaced from the first named vertical leg, and a return portion connecting the upper ends of said vertical legs; passage means connected with said path remote from said first named vertical leg providing for the introduction of gaseous medium and solid material to be comminuted into the circulation in said closed path, passage means connected to said path at a point remote from said first named vertical leg and between said first named vertical leg and the connection of the said first named passage means with said path for the removal of gaseous medium and comminuted solid material from said closed path; a propeller type axial fiow fan disposed for rotation about a, substantially horizontal axis extending centrally along said horizontal leg, said fan being located adjacent to said zone and effective to move said gaseous medium and said solid material suspended therein along said horizontal axis and through said horizontal leg toward said first vertical leg, a second propeller type axial fiow fan disposed for rotation about a substantially vertical axis centrally of said first named vertical leg, said propeller type fan being located adjacent to the lower end of said first named vertical leg and arranged to cause upward movement of the circulating medium and suspended materials in said first named vertical leg, and bearing means for supporting each of said fans in different axially adjusted positions. whereby controlled turbulence is created in selected parts of said path tending to control the rate and degree of the comminuting action on the suspended solid material.

6. An attrition mill, comprising means forming a closed circulatory path for a gaseous medium and a solid material which is to be comminuted in said mill and which is in suspension in said gaseous medium, said path forming means including a substantially cylindrical portion pro- 7 viding a substantially vertical leg of said path. a substantially horizontal leg of said path provided by a cylindrical lateral extension of said portion intersecting said vertical leg adjacent to the lower end thereof, a second substantially cylindrical vertical leg intersecting said horizontal leg at a zone spaced from the first named vertical leg ,and from the-lend of said horizontal leg remote from said named vertical leg, and a U-shaped return portion connecting the .upper ends of said vertical legs, said horizontal and vertical legs having substantially greater cross sectional areas than that of said return por- 1 tion; a propeller type axial flow fan disposed for rotation about a substantially horizontal; axis coaxial of said horizontal leg, said fan being located adjacent to said zone and effective to move said gaseous medium and the solid material suspended therein along said horizontal axis and through said'horizontal leg toward said first named vertical leg; the portion of said horizontal leg between said fan and the remote end thereof providing a receiving chamber for material to be comminuted and gaseous medium, passage means chamber for the introduction of gaseous medium and solid material to be comminuted, passage means connected to said return portion for the removal of gaseous medium and comminuted solid material from said path; a second propeller type axial flow fan disposed for rotation about a substantially vertical axis coaxial with said first named vertical leg, said second fan being located connected to said receiving.

adjacent to the lower end of said first named vertical leg and arranged to cause upward movement of the circulating medium and suspended.

rate and degree of the comminuting action on.

the suspended solid material.

HENRY L. CROWLEY. EDWIN F. MOSTHAF. ASHLAND S. HENDERSON.

nEFERENoEs erran The following references are of record in. the file of this patent:

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